Of course you're going to get biased answers here, but I agree that the M3 is more reliable than a 135i, though running costs will undoubtedly be higher. I'd check with your insurance and such and then try to test drive an M3; just make sure to do a proper test drive, i.e. stay ABOVE 4K and in lower gears for extended periods, because if you just cruise around it won't feel as special. Then make your decision from there -- though I'll give you fair warning. If you test drive an M3, you WILL want to buy it.

Having driven an M3 and a 1M (never a 135i, sorry), I came to appreciate the 1M as a car that's far easier to accelerate quickly at civilized RPMs in casual driving scenarios and thus can make sense for someone who just needs a fun DD. But when you want to really go out and DRIVE, there's no comparison to the M3. Just make sure you'll be visiting a track or at least some twisty back roads frequently just for the pure joy of driving, because if you do nothing but DD your M3 along city streets and freeways, you'll probably see it as a waste because your current car is better for that. But honestly, even twisty back roads don't compare to the track in terms of helping you appreciate the M3's existence in this world.

Also, if you buy the M3, since it's an 08, try to get your software updated at the dealer. A friend of mine still had the original factory software and got the latest stuff, said it definitely improved the engine feel, which seems to be others' impressions with the very latest round of updates.

Thanks for all the responses and advice. I will definitely enquire about the software upgrade.

I was also advised to install the performance exhaust on the M3. Is this worth it? I must admit, I will miss the 135, especially the sound of the turbos.

I briefly considered that, but the general answer is that most exhausts are purely audio candy; a few of them will give some power gains, but not enough that that should be your motivating factor. Personally I think you'll be so happy with the stock sound compared to your 135i that you won't feel any immediate urge to make it "better".

But at the end of the day, I decided that I love the stock sound because it sounds like a muscle car below 4K RPM and starts channeling F1-style banshee wails above 4K all the way to redline. And the M Performance Exhaust is FAR more expensive than other solutions, so the advice about hearing an exhaust you're considering in person before pulling the trigger applies even more with that exhaust. But IMHO, there are better ways to spend that amount of cash. For me, since I'm rapidly developing a track addiction, I would sooner buy a set of dedicated track wheels and tires as well as adjustable camber plates to get a square setup with more negative camber in the front so I can reduce the built-in understeer this car has. But that's only something I feel the need for on the track; if you regularly encounter this car's understeer on public roads, you're driving way too hard for that environment. After that I would probably get a BBK. Add the fact that I'd also like to set up a projector-based home theater system and an exhaust fell very rapidly down my list of priorities.

Bottom line: Get a feel for (and enjoy!) what you have before you start thinking about ways to change it. You might be surprised how little you end up thinking needs "improvement".

try { Life.Live(); } catch (Experience exp) { Console.WriteLine(exp.ToString(); } finally { Brian.Dispose(); }
"There are only 10 kinds of people in the world; those that read binary, and those that don't."

I will toss my hat into the ring on this one. I just bought a 2011(NOV/10 build) e90 DCT on Wednesday so I just made the move. For me every BMW should have a Sport package and i have had a few. Actually, i have owed/own 8 bimmers and all have had V8's.... anyway..... M cars are so much more than your STD BMW. I am absolutely amazed at just how "raw" the M3 is compared to your non "M" version is. Until you own one it is hard to understand. You can buy and MOD a (#) series and have HP/torque numbers which are close to an M car but that does not tell the whole story. The sounds, feedback, suspension, chassis are tuned to work together compared to the std BMW. Don't get me wrong, the std BMW is a great car but the M is just so much better. When realize you are at 4k on the tach and you are only 1/2 way to redline and then you actually shift at 8x00 rpm you will realize... and don't forget the car is screaming

Before I bought the M3 I talked to my SA (which is a good friend) about the e9x and what his opinion was. He told me that he rarely sees a e9x in the shop for anything than std/accelerated maintenance and minor warranty stuff(cup holder, interior parts "excessive wear" ect. Absolutely bullet proof if you change the fluids on the old school schedule. I have had a 2004 545(e60 first year) which had 30k worth of warranty work done aka everything replaced, 2007 X5(e70 first year) which had many issues, a 2011 E70 which spent 60 days straight in the shop after owning it for 4 months before it was lemon-ed and BMW gave me a new 2012 to replace it with more options for the trouble. If my SA tells me e9x M3 is bullet proof, I believe him.